Flat-panel display devices, such as liquid-crystal, plasma, and OLED displays are becoming increasingly large. While it is well known that increasing the size of the display generally benefits the user by allowing him or her to view more information simultaneously and to reduce the amount of input device movement necessary to swap screens in and out of focus, the use of large flat desktop display monitors also have significant disadvantages.
One of the most significant disadvantages of a large, flat desktop display can be illustrated by considering the scenario that occurs when the user positions his or her head to a viewing distance that allows him or her to comfortably view information in the center of the display screen. For a small display, information at the edges of the display is at approximately the same viewing distance as the information at the center of the display. However, as the horizontal dimension of the display is increased significantly, the viewing distance to the edges of the display increases significantly if the user maintains their original head position. This can make it difficult for the user to see the information at the edges of the large desktop display without making strenuous whole-body movements that are required to bring their eyes closer to the edge of the display. One way to overcome this problem is to utilize a display that is not flat.
Curved displays have been discussed both for group and individual viewing. However, the design constraints for such systems differ significantly since the shape of the surface may be optimized for an individual's performance when designing displays, such as desktop monitors, while many users must be able to comfortably view displays used for group viewing in applications such as a cinematic or data presentation. Further, since large displays designed for group viewing are typically several meters or more in width, they are typically viewed at a viewing distance of several meters while desktop monitors designed for use by an individual are usually 2 meters or less in width and are viewed from a viewing distance of a few decimeters. Since the viewing distance to displays for group viewing is significantly larger than the viewing distance to displays intended for use by a single individual, the users of displays for group viewing will be less sensitive to changes in the radius of curvature of these large displays than a user of a smaller display that is designed to be used by an individual within a typical computerized desktop working environment.
The need for large, non-flat displays that are designed for use by a single user has been recognized within the field of aircraft simulation for several decades. For example, U.S. Pat No. 3,514,871 entitled “Wide angle visual display” discusses a flight simulation system utilizing three individual display modules that are configured to produce a single display system, wherein the center display module is oriented perpendicular to the user's forward line of sight and the two neighboring display modules are angled such that the ends of the neighboring display modules furthest from the center of the center display module are closer to the user than they would have been had the display modules all been placed on a plane perpendicular to the user's line of sight. While this disclosure does not explicitly discuss the angles of these display modules to one another, other than to state that they are “circumferentially spaced” about the user to provide greater clarity and detail, the Figures within this disclosure show the centers of the display modules as all being equally spaced from the user. Note that by placing the center of the display modules at equal distances from the user, the viewing distance is approximately equal at each point on the final display surface.
Displays that provide equal viewing distance at every point are also described by U.S. Pat. No. 5,275,565, entitled “Modular display simulator and method,” which discusses the use of multiple display modules to compose a display. This patent further discloses display modules being oriented such that the resulting display at the center of each of the display modules is perpendicular to the user's line of sight as he or she turns his or head to look at them and shows display modules that are each positioned to be viewed from an equal viewing distance.
Display surfaces for a single user wherein every point on the display surface is equally distant from the user's eyes is also discussed in U.S. Pat. No. 4,740,779 entitled “Aircraft Panoramic Display”. Within this disclosure it is stated that the ideal means for generating information for such a display includes the “means for determining the position of a great circle on a sphere having its center at the position of a great circle on a sphere having its center at the eye point”, which indicates that a display formed from a portion of a spherical surface would ideally have a radius of curvature equal to the user's preferred viewing distance. This physical arrangement is clearly demonstrated within FIG. 5 of U.S. Pat. No. 4,740,779. This patent further states that when multiple displays are provided the display screens are positioned such that “a line normal to a portion of each display screen passes approximately through the eye point”, further indicating equal viewing distance to various points on the display surface.
For a given viewing distance, as the curvature of the display surface is increased from a flat to a cylindrical surface having a radius of curvature equal to the user's viewing distance, the horizontal field of view of the display (i.e., the subtended angle of the display on the human's retina) increases. This is important since it is known that as the field of view of the display is increased, the user will have an increased sense of immersion when using the display. That is, a user will feel more like they are “in the display” rather than just looking at the display when the display field of view is large. This increased sense of immersion has been shown to improve user performance and enjoyment within applications where it is important that the display provide the perception of working within a virtual reality. Therefore, it is well established in the prior art that a large field of view, curved personal display would ideally have a radius of curvature near or equal to the user's viewing distance.
While the use of curved displays for simulation, virtual reality, and group presentation venues has been addressed extensively within the patent literature, the use of curved displays for desktop office use has been addressed to a much lesser extent. Ergonomic visual display terminal (VDT) desktop standard ISO 9241-5 entitled “Ergonomic requirements for office work with visual display terminals (VDTs)” states that the optimum viewing distance for office work in the seated position is 600 mm. Based upon the simulation and virtual reality display prior art, one should accordingly expect the ideal radius of curvature for a cylindrically shaped display intended for desktop use to be 60 cm.
U.S. Pat. No. 6,813,074, US20030223113, and US20040239890 A1 all entitled “Curved screen immersive rear projection display” describe an immersive rear-projection display for use as a desktop monitor that is capable of providing aspect ratios of 2.66:1 or 4:1, or even greater on a curved display surface. As stated by the author, this display design allows viewers to be “immersed” in the images being displayed because the images can encompass both the direct and the peripheral views of a user. In one implementation, the immersive rear-projection display includes two or more electronic projectors (e.g., three) that are positioned behind a curved translucent display screen. The electronic projectors project respective display images adjacent each other onto the display screen. In one implementation, the curved display screen is formed as a generally continuous curve with substantially no discontinuities in the curvature. Also, the curved display screen may be formed with a generally consistent radius of curvature (i.e., generally as a circular or cylindrical segment), or without a generally consistent radius of curvature, such that the shape of the curve “reduces or eliminates perspective distortion that can otherwise occur at the edges of a flat screen.” The complete elimination of perspective distortion typically will require a constant viewing distance to each point on the display surface. This disclosure, however, also includes an example of a display having a radius of curvature of about 86 cm (34 inches) with a height of 30 cm (12 inches) and a length of 120 cm (48 inches). This example would require a relatively large viewing distance (86 cm) to eliminate perspective distortion. While it may be possible to utilize projection displays within a desktop environment, such a solution is not desirable simply because of the volume of desktop space these displays will consume. Further, the disclosed projection display embodiment may not optimize the degree of curvature for viewer preferences in desktop environments.
Curved flat panel displays are also known in the prior art. For example, U.S. Pat. No. 6,332,690, discloses a liquid crystal display with a curved screen. The display surface of the screen is disclosed as possibly being curved forwards, as well as rearwards, to be a wholly or partially quadratic or higher-degree surface, such as a cylindrical surface about a vertical, oblique or horizontal axis, a parabolic or hyperbolic surface, or a spherical surface, alone or in combination. Note that besides providing a thin display, the use of flat panel technology also increases the flexibility to select different shapes and degrees of curvature over what is possible using projection technology since the shape of a projected image is limited to shapes that can be formed using projection optics. The use of projection optics often imposes limits on the degrees of curvatures that can be obtained as well as the overall shape of the display surface as it is difficult, if not impossible, to produce display surfaces having an instantaneous change in curvature using a projection lens without introducing artifacts. However, as long as curved flat panel devices can be formed, they may take on practically any degree of curvature or shape. Despite the fact that U.S. Pat. No. 6,332,690 acknowledges the flexibility to select from among a large range of display shapes and curvatures, this disclosure does not specifically discuss the preferred shape of such a display for a desktop environment.
Applicants have determined, however, that the prior-art cylindrical or spherical display surfaces having a constant viewing distance across the horizontal dimension are not optimized for comfortable and efficient use as desktop displays in computer information applications. There is a need, therefore, for curved flat panel desktop display devices having display surfaces that provide a more desirable tradeoff between a display surface that is always at a single viewing distance, as is the case for desktop displays having a circular shape along their horizontal dimension with a radius of curvature equal to the design viewing distance of the display device, and a display surface that is flat.